Marcus,

Thank you very much. I had Calendar-A wrong (a blooper) and resource loading also (not a blooper).

Now I should be able to investigate the model further, definitively this is an issue of most interest to me as such constraints happen every day in my schedules.

Best Regards, Rafael 

sprj

https://www.dropbox.com/s/ga95pdf88o4ahwm/C%26I.001.sprj?dl=0

Marcus, thanks for the video, got the link and downloaded the video using 4k video downloader. I missed the interruptable issue I got to further explore and keep documented.

Advanced Features of Spider Project.pdf

Page 5 of 59 - Among other activity properties it is practical to define if its execution shall be continuous. If Yes then an activity shall not start if it could not be finished until the end of the work day (an example - concreting).

It is more than this and better. 

Continuous period means a period of work with no interruption; lunch break is an interruption while change of day does not necessarily break continuous work.  If activity is set to start at the beginning of a continuous period it will not be delayed, if activity is set to start after beginning of the period but can finish within the period it will not be delayed, otherwise will be delayed to start at the beginning of next continuous period. 

Continuous work is different to start hour constraint.  The problem with the start milestone approach is that while a real constraint model it is convoluted and error prone.  Maybe instead of start hour constraints an activity start calendar would be better as it will give you control of start hours as well as days; it is common requirement not to allow start of some activities to be at the end of the week.

No matter what the DD it should work as expected. Even if you force the DD to be at the start of the work day there are many possible reasons for the activities wanting to start not at the beginning of the day.

At home a real constraint is for some activities not to start on late hours but on the next day. Moving crews along with their equipment to start late in the day new activities is not always a good idea.  

• We start from 7:00 to 10:00 am pouring concrete on slabs but not later.
• We start cement plaster at 6:00 to 7:00 if not we start next day.
• And the list goes on.

Unfortunately there is no such thing as a Start no Later than XX:XX Hour.

By the same token we start some activities late in the afternoon but not so late as to get into much overtime or to be finished on next day. In other words some activities have a Start no Earlier than XX:XX Hour and a Start no Later than YY:YY Hour

Hour constraints do happen, whether you like it or not!

To fix the start&finish of milestone to make sure activity starts at the beginning of the day; say 6:59 - 7:00 can be error prone, so for this application it might be better to make lunch time a work hour.  

I would leave such approach to limit a time window such as to start between 7:00 - 12:00 in order to avoid starting the activity late in the day. In other words, Start Hour No Later than 12:00. Allowing an activity to start during the last hours of the day is not always a good idea.

Daniel,

you have lunch break in your calendar.

An activity cannot start and finish before the lunch break and so it starts after lunch.

It did not help because its duration is larger than the work time after lunch.

If your start milestone starts at the start of the work day, or at any time after lunch your will get the expected schedule.

I downloaded the file and calendar B is used on some lags that are filtered but could not see this calendar on the calendars view, maybe the file is corrupted.

I created a simple file and it works as expected, as always.